The present invention disclosed herein relates to an X-ray and a method of focusing electronic beams, and more particularly, to a field emission X-ray tube and a method of focusing electronic beams using the same.
X-rays generally used for medical purposes, industrial purposes, and research purposes are obtained by colliding electrons on an anode electrode of a metal target, in which, as an electron source used for this, there are a thermionic source including electron discharge by heating a metallic material and a field emission source using nano materials.
Thermionic sources have a relatively short lifespan, are difficult to reduce a size thereof. Also, since electron discharge is performed as a dipole, it is difficult to control the strength of an X-ray and difficult to perform integration, and miniaturization thereof. On the contrary, in case of field emission sources using nano-materials, it is possible to discharge electrons as triode structures, to have various electric, physical shapes, to generate X-rays with relatively higher outputs than thermionic sources, and to easily perform controlling the strength of X-rays, integration, and miniaturization thereof. There have been many researches to apply field emission sources to industrial defect and quality inspection systems, medical brachytherapy systems, and three-dimensional digital diagnosis system using such merits of field emission sources.
However, there are some limitations on nano-material-based field emission sources in aspect of technologies up to now. When field emission occurs, there is a limitation of present electron beam focusing, which should be priorly solved. As the limitation occurring due to omission of electron beam focusing, there is electric charge accumulation occurring on a sidewall of ceramic used for insulation in such a way that electron beams are not transmitted to an anode electrode, thereby preventing generation of X-rays, an electronic source is damaged and demolished due to arcing, and it is impossible to form focal spots in sizes of micro meter μm or nano-meter nm to obtain an X-ray image with high output and high resolution.
To overcome such limitation, it is needed to provide a gate electrode structure including electron beam focusing of a new concept and to provide a vacuum seaming technology for manufacturing an X-ray generator such as an X-ray tube.